The tools of the invention are of a type including a body structure which is adapted to be held and be manipulated by a user, and which carries an air motor driving a head to which a sheet of sandpaper or other abrading or polishing element is connectable. The motor has a housing containing a chamber defined by top and bottom walls and a side wall, with a rotor being located in the chamber and connected to a shaft journaled for rotation about an essentially vertical axis by upper and lower bearings carried by the top and bottom walls respectively. The shaft is operatively connected beneath the lower bearing to the polishing or abrading head.
In prior devices of this type, the contact of the undersurface of the rotor with the bottom wall of the housing has tended to produce wear on both of these surfaces ultimately causing excessive leakage of air between those surfaces decreasing the efficiency and maximum speed of operation of the tool. Also, air has tended to leak downwardly from the motor chamber though the lower bearing carried by the bottom wall of the housing, with further decrease in operating efficiency and adverse effect on the bearing. This air leaking downwardly may carry contaminants into the bearing and may force grease or other lubricant from the bearing, both of which effects can reduce the overall effective life of the bearing and motor.